Junceellin and praelolide, two briaranes from the gorgonian corals Junceella fragilis and Junceella juncea (Ellisellidae)

Natural Product Chemistry of Gorgonian Corals of Genus Junceella–Part III

“…Of the briaranes, 50 compounds are halogenated (50/75 = 66.7%). Briarane-type natural products are a large family of natural products that are only isolated from marine organisms and the compounds of this type were suggested originally synthesized from the 3,8-cyclization of cembranoids by the host corals and not by their zooxanthellae [ 37 , 53 , 54 ]. Briarane-type diterpenoids continue to attract attention owing to their complex structures and potential biomedical activities.…”

“…Two new briaranes, fragilides K ( 58 ) and L ( 59 ), along with five known chlorinated briaranes, gemmacolides V ( 60 ) and X ( 61 ) [ 31 ], praelolide ( 62 ) [ 7 , 14 , 16 , 32 , 33 , 34 , 35 , 36 , 37 ], and juncins P ( 63 ) [ 35 ] and ZI ( 64 ) [ 11 ], were obtained from a Formosan J. fragilis [ 38 ] ( Figure 5 ).…”

“…Four new briaranes, junceellolides M–P ( 65 – 68 ), along with seven known briaranes, junceellolides A–D ( 21 , 22 , 69 , 70 ) [ 14 ] (the structures of briaranes 21 and 22 , please see Figure 2 ), junceellin A (= junceellin) ( 71 ) [ 7 , 14 , 16 , 34 , 35 , 36 , 37 , 39 , 40 ], praelolide ( 62 ) [ 7 , 14 , 16 , 32 , 33 , 34 , 35 , 36 , 37 ], and juncin ZI ( 64 ) [ 11 ] (the structures of briaranes 62 and 64 , please see Figure 5 ) were isolated from J. gemmacea , collected from the South China Sea [ 41 ] ( Figure 6 ). The structures, including the absolute configurations, of new briaranes 65 – 68 were deduced on the basis of spectroscopic analyses, particularly with ECD experiments.…”

“…Three known briaranes, junceellolide A ( 21 ) [ 14 ], praelolide ( 62 ) [ 7 , 14 , 16 , 32 , 33 , 34 , 35 , 36 , 37 ], and junceellin A ( 71 ) [ 7 , 14 , 16 , 34 , 35 , 36 , 37 , 39 , 40 ], (the structures of briaranes 21 , 62 , and 71 , please see Figure 2 , Figure 5 , and Figure 6 , respectively), and a known sterol, 5α,8α-epidioxy-24(ξ)-methylcholesta-6,22-dien-3β-ol ( 80 ) [ 48 ] ( Figure 9 ), were obtained from the ethanol extract of a gorgonian coral identified as Junceella sp., collected off the Vietnam Thu Island in May 2010 [ 49 ]. However, by assuming that enantiomeric series for sterols, the configuration at C-24 in 80 should be assigned as S *-form on the basis of the 13 C NMR chemical shift of C-24 and C-28 [ 50 ].…”

Briarenolides K and L, New Anti-Inflammatory Briarane Diterpenoids from an Octocoral Briareum sp. (Briareidae)

“…Briarane-type natural products are found only in marine organisms and mainly from octocorals [ 1 , 2 , 3 , 4 , 5 ]. The compounds of this type are suggested to be originally synthesized by host corals [ 6 , 7 ] and have been proven to possess various interesting bioactivities [ 1 , 2 , 3 , 4 , 5 ]. The octocorals belonging to the genus Briareum (phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Gorgonacea, suborder Scleraxonia, family Briareidae) have been proven to be the most important source of briarane analogues [ 1 , 2 , 3 , 4 , 5 ].…”